Increasing geotechnical design efficiency by virtue of HTEM sediment mapping

A new road segment is being planned northeast of Norway's capital city, Oslo. In this context, knowledge of sediment thickness is vital, as is information about occurrence and extent of highly sensitive marine clay (so-called quick clay). Airborne EM measurements were conducted to provide information of depth to bedrock/sediment thickness between drilling sites and guide the further drilling program. AEM data indicate a variable bedrock depth with a general trend towards shallower bedrock in the northeastern part of the investigation area. Quick clay is not easily identified in the AEM data, but some possible occurences agree well with the results from drillings. Based on the AEM results recommendations for further drillings were given, thus reducing the overall costs of the project.